1. Field of the Invention
The present invention relates to a high precision toothed part, or gear, having a shaft and a method of molding the same. Such parts are frequently used within the automatic transmissions of automobiles.
2. Description of the Related Art
In conventional methods for forming this type of gear with a shaft, the shaft part and the flange part are difficult to mold or form as a unit. In a first conventional method, a shaft part and a flange part are molded separately, and then welded together afterwards. The first conventional method requires anti-carburizing and pre-processing for welding. The first conventional method also required a separate jig for holding the parts during welding. Since heat is used during the first conventional method, there are associated heat deformation problems resulting in precision losses and high production costs.
Referring now to FIGS. 6(A) and 6(B), an alternative second conventional method exists for forming this type of gear with a shaft. In the second conventional method, the part and shaft are molded from an initial unitary object. In this method, a raw material 20 is formed in to an intermediate product 21. Raw material 20 is constructed from a disk-shaped flange part 20a and a cylindrical shaft part 20b. A tubular part 21 a and a bottom part 21b are formed by backwards extruding flange part 20a. Upon completion of the backwards extrusion intermediate product 21 is completed but requires further complex processing before reaching a final form.
This second conventional method requires very high pressure to achieve the backwards extrusion of flange part 20a. Due to the high extrusion pressure, the life span of an extrusion die is short and the cost for construction for the die and other extrusion equipment is high. The high extrusion pressures also requires intermediate product 21 to have an undesirable thick bottom part 21b and tubular part 21a. The backwards extrusion method has poor net shape rate result and production losses are high. Finally, this molding method is difficult to apply to large parts.
It is an object of the present invention to provide a high precision method of molding.
It is another object of the present invention to provide a method of molding a toothed part with shaft that has high precision.
It is another object of the present invention to provide a toothed part with shaft that has high precision, high rigidity, and strength.
It is another object of the present invention to provide a method of molding a toothed part with hollow shaft and a flange constructed from a bottom part.
It is another object of the present invention to provide a method of molding a tubular part, or a flange constructed from a tubular part, and disk part.
It is another object of the present invention to provide a method of molding teeth on a tubular part or on a shaft.
It is another object of the present invention to provide a combination of plastic working steps in a method for producing a final product with precise dimensions and low loss rates.
It is to be understood that the word plastic, or plastic working applies to the material being malleable or deformable during a working process and does not require a carbon material, or any other specific material, to be used with the method.
Briefly stated the present invention relates to a method for producing a unitary toothed part and a shaft and the resulting products. In the process, a blank is formed. The blank includes a shaft part and a flange part. The flange part having a thicker outer diameter and a thinner inner diameter. The outer diameter is formed into a tubular part by drawing. A plurality of teeth and remnants are formed by extruding the tubular part. At least one spline is formed by extruding the shaft part. Through the steps of forming, drawing, and extruding a blank is made into a unitary part having teeth and a shaft thus increasing precision, rigidity, durability, and reducing forming costs.
According to an embodiment of the invention, there is provided a method for molding a toothed part with a shaft comprising the steps of: forming a raw material blank, the raw material blank includes at least a flange part and a shaft part coaxial and perpendicular to the flange part, drawing a tubular part, the tubular part on a first part of the flange part, parallel to and away from the shaft, extruding a plurality of teeth portions, the teeth portions on the tubular part disposed on an outer surface of the tubular part away from the shaft part, and extruding at least a first spline, said spline on the shaft part.
According to another embodiment of the present invention, there is provided a method for molding a toothed part with a shaft, further comprising the steps of: forming the flange part into a large diameter part and a small diameter part, the large diameter part being the first part and larger than and concentric to the small diameter part, and the large diameter part being thicker than the small diameter part, and forming a plurality of remnant parts by extrusion, the remnant parts between the tubular part and the shaft part interposed with the plurality of teeth.
According to another embodiment of the present invention, there is provided a method for molding a toothed part with a shaft comprising the steps of: forming a raw material blank, the raw material blank includes at least a flange part and a shaft part coaxial and perpendicular to the flange part, drawing a tubular part, the tubular part on a first part of the flange part, parallel to and toward the shaft, extruding a plurality of teeth portions, the teeth portions on the tubular part disposed on an outer surface of the tubular part toward the shaft part, and extruding at least a first spline, the at least first spline on the shaft part.
According to another embodiment of the present invention, there is provided a method for molding a toothed part with a shaft, further comprising the steps of: forming the flange part into a large diameter part and a small diameter part, the large diameter part being the first part and larger than and concentric to the small diameter part, and the large diameter part being thicker than the small diameter part, and forming a plurality of remnant parts by extrusion, the remnant parts between the tubular part and the shaft part interposed with the plurality of teeth.
According to another embodiment of the present invention, there is provided a toothed element, comprising: a shaft part and a tubular part extend coaxial along a central axis, the tubular part extends in a first direction along the central axis, a bottom part extends perpendicular to the axis between the shaft part and the tubular part, the tubular part has a first outer surface opposite to the central axis, the shaft part has a second outer surface opposite to the central axis, a plurality of teeth on the first outer surface, a plurality of extrusion remnants interposed between the teeth on the first outer surface, and at least a first spline on the second outer surface.
According to another embodiment of the present invention there is provided a toothed element, wherein: the first direction is parallel to and away from the shaft part.
According to another embodiment of the present invention there is provided a toothed element, wherein: the first direction is parallel and concentric to the shaft part.
According to another embodiment of the present invention there is provided a method of molding a toothed part with a shaft, comprising the steps of: forming a flange part and a shaft part having a common center axis, drawing the flange part into a tubular part and a bottom part, and extruding the tubular part to form a plurality of teeth.
According to another embodiment of the present invention there is provided a method of molding a toothed part with a shaft, wherein: forming a flange part and a shaft part is conducted by cold forging.
According to another embodiment of the present invention there is provided a method of molding a toothed part with a shaft, wherein: the flange part includes a large diameter part and a small diameter part, the large diameter part having a thickness greater than a thickness of the small diameter part.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate similar elements.